A tire and wheel assembly commonly comprises a rim and a pneumatic tire mounted to the rim. The pneumatic tire typically includes a ground-supporting portion and a pair of sidewall portions which define an inflation chamber. If, for example, the inflation chamber is free from intermediate supporting structure, regions of the sidewall portions will collapse into each other when the tire becomes deflated or in an otherwise under-inflated condition. This will result in internal tread-adjacent regions contacting internal rim-adjacent regions during an under-inflated condition. The tread-adjacent region is usually just radially inward of the tire's tread edge and the rim-adjacent region is usually just radially outward of the rim.
In the event of an under-inflated condition, commonly called in the extreme a “flat tire”, it is usually necessary to drive the vehicle for at least a limited distance to remove the vehicle from the flow of traffic and/or to transport the vehicle to a repair location. During this driving period, there is the possibility of lateral movement between the deflated tire and rim. Specifically, the ground-engaging portion of the tire is not held sufficiently rigid and “wobbles” during the flat tire driving period and the deflated tire actually rides on its collapsed sidewall portions. This can result in destruction of the tire and/or the vehicle moving in an uncontrolled manner out of the prescribed direction of travel under the influence of forces brought about by the under-inflated condition of the tire. In the extreme, the tire can separate from the wheel, causing the driver to attempt to operate the vehicle by driving on the metal rim, a very unsafe and damaging situation.
In the past, attempts have been made to improve the run characteristics of a tire and wheel assembly in an under-inflated condition. These attempts have included mounting stabilizing members on the rim of the wheel (see e.g., U.S. Pat. No. 3,288,193 to Mantzel and U.S. Pat. No. 4,767,288 to Zinnen), substantially increasing the thickness/stiffness of the ground-engaging or sidewall portions (see e.g., U.S. Pat. No. 3,734,157 to Roque, U.S. Pat. No. 4,405,007 to Welter, and U.S. Pat. No. 4,467,852 to Ippen), and/or providing safety supports that occupy a substantial amount of space within the inflation chamber (see e.g., U.S. Pat. No. 3,610,308 to McDonald, U.S. Pat. No. 4,722,377 to Dobson, and U.S. Pat. No. 5,891,279 to Lacour). While such techniques can improve run flat characteristics, they tend to add a significant amount of excess mass, complicate manufacturing procedures and/or require the mounting of extra structural pieces on the rim or within the tire.